Electrical starting and generating system



Jan. 5, 1943. M. H. ELKlN ELECTRICAL STARTING AND GENERATING SYSTEM Filed June 24, 1941 Patented Jan. 5, 1943 ELECTRICAL STARTING A ND GENERATING SYSTEM Manuel H. Elkin,

Elmira Heights, N. Y., assignor to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application June 24, 1941, Serial No. 399,491

4 Claims.

The present invention relates to an electrical starting and generating system and more particularly to a motor generator system in which a single electrical unit is used first as a motor to crank the engine and then as a generator to supply electrical power.

In systems of this kind it is customary to provide a driving connection from the electrical unit to the engine having a high mechanical advantage for cranking the engine, and a connection from the engine to the electrical unit having a lower ratio for driving the electrical unit as a generator.

One form of cranking connection in common use is the so connected to the electrical unit as to be automatically meshed with an engine gear upon actuation of the unit as a motor, and automatically demeshed when the engine starts. Commercial units for automatically controlling the actuation of such starter drives have been developed based on the disclosure of Loehr and Burdick, Patent No. 1,894,970, but these units as now manufactured are not adapted to control the starting operation in single unit motor generator systems.

It is an object of the present invention to provide a novel starter control for single unit motor generator systems which is reliable and efiicient in operation and simple and economical in construction.

It is another object to provide such a device which adapts to such a single unit system certain principles and features which have been used successfully in connection with other forms of starting and generating systems.

Further objects and advantages may be apparent from the following description taken in connection with the accompanying drawing which illustrates semi-diagrammatically an electrical system embodying a preferred form of the invention.

In the drawing there is illustrated a starting system for an internal combustion engine not illustrated, comprising a battery I grounded at 2 and connected by a lead 3 to a starter control unit indicated generally by numeral 4. This control unit comprises a magnetic starting switch 5 having a fixed contact 6 to which the battery lead 3 is connected, a second fixed contact 1 and a bridging contact 8 arranged to be actuated by a solenoid coil 9. Contact 1 is connected by lead ll through a single turn series coil 12 to a lead l3 which is connected to an electrical motor generator unit I 4.

The motor generator comprises an armature .1

Bendix drive which embodies a pinion l5, a series field l6 which is used for starting purposes only, and a shunt field H, the strength of Which may be regulated by a variable resistance I 8 in order to control the out-put of the unit as a generator. One terminal of the motor generator is grounded as indicated at l9 and the other terminal is connected through a lead 2| and an ammeter A to an automatic cut-out switch 22.

A control circuit for the magnetic starting switch 5 is provided, comprising a manually operable control switch 23 connected by a lead 24 to the battery lead 3 and by a lead 25 to one end of the starting switch solenoid 9. The opposite end of the solenoid 9 is connected by a lead 26 to a fixed contact 21 which is normally enwardly so as to open of coil 31 is grounded tact 4| placed in the the voltage of the generator as long as the motor generator is being driven as a generator. Coil 42 is also energized by battery the cranking operation to assist open contacts 21, 28

A charging circuit the coil 37 to when the engine starts. for the battery I from the bridged by means of leads minals 49, 5| on a control panel 52, which terminals may be connected by suitable switch means to bring into effect the high charging rate. It will be understood that the control switch 23 and the control panel 52 are of conventional form and form no part of the present invention so that further description thereof is deemed unnecessary, it being merely stated that when the control switch is in the position illustrated, the device is rendered inoperative, while movement of the switch 23 to its lower position causes closure of the control circuit and consequent actuation of the starting mechanism to place the unit in service.

In operation, closure of the control switch 23 completes the control circuit from battery I through leads 3, 24, and 25, magnetic switch coil 9, lead 26 and contacts 21, 28 to the ground at 3| whereby said coil is caused to close the magnetic switch 5. The starting circuit is thereby completed from battery I through lead 3, contacts 6, l, 8, lead I l, coil I2, lead l3 to the motor generator through its series field It. The motor generator is thereby motorized to crank the engine.

Closure of magnetic switch causes energization of the relay coils 31 and 42, but since the single turn series coil I2 is at this time energized by the heavy cranking current, the coils 31 and 112 are unable to overcome the effect on the core 36 of the coil l2, and the core 36 is not moved from the position illustrated. When the engine starts, however, the load on the starting circuit is released, thus reducing the flux through the series coil [2 and increasing the voltage applied to coils 3'! and 42 whereby these coils are able to overcome the coil l2 and move the core 36 so as to swing the relay arm 34 down and open'contacts 21, 28. This breaks the control circuit causing the starting switch 5 to open. The coil 42 however is maintained energized by current generated by the motor. generator as driven by the engine and thereby holds the relay contacts 21, 28 open as long as the engine remains self-operative. Should the engine stop for any reason, however, the consequent deenergization of the coil 42 allows the relay arm 3 to move up to its original position by virtue of spring 53. The coil 9 of the in the design and arrangement of the parts without departing from the spirit of the invention as defined in the claims appended hereto:

What is claimed is:

1. In an electrical starting and generating system, a motor generator unit, means for energizing said unit as a motor to crank the engine including a battery and a magnetic starting switch, manually controlled means for closing the switch, means for maintaining the switch closed until the engine starts, means including a coil connected to the motor generator unit by magnetic starting switch is not immediately reenergized, however, since the weight 32 is set into vibratory motion when it is released by the relay arm, so that the contacts 21, 28 do not come into effective engagement for a pre-determined time after such release. This time is so arranged as to permit the engine and motor generator sure of the starting switch. This insures that the cranking connection from the motor generator to the engine is properly established in an automatic manner.

When the engine drives at or near its normal speed, the voltage of the generator causes the cut-out switch 22 to close, whereby the charging circuit for the battery is completed, and power is supplied to the line terminals 49 and 54 on the control panel 52.

Although but one embodiment of the invention has been shown and described in detail, it will be understood that other embodiments are possible and that various changes may be made to come completely to rest before 010- the motor generator closure of the starting switch causing the starting switch to open responsive to self-operation of the engine, means including a coil energized by said unit acting as a generator for preventing actuation of the switch-closing means, means including a coil actuated by voltage of the unit as a generator higher than battery voltage for establishing a charging connection from the generator to the battery, means for breaking this connection if the generator voltage drops below the battery voltage, and means for delaying reclosure of the starting switch for a predetermined time after the motor generator has come substantially to rest.

2. In a single unit starting and generating system for internal combustion engines, a motor generator unit, a starting circuit therefor including a battery, and a magnetic starting switch, a control circuit for the magnetic starting switch including a pair of normally closed contacts, electro-magnetic means connected to the starting circuit by, closure of the starting switch for opening said contacts when the engine starts, electro-magnetic means connected to the starting circuit and energized by the motor generator unit for holding the contacts open while said unit is driven by the engine as a generator and means for preventing effective re-closure of the contacts for a predetermined time after the unit has come substantially to rest.

3. In a single unit starting and generating system for internalcombustion engines a motor generator, a battery, a starting circuit including the motor generator, the battery and an electromagnetic starting switch; a control circuit for the switch including said battery, a control switch and an electro-rnagnetic relay; a coil in series in the starting circuit for holding the relay closed during cranking, a coil tapped into the starting circuit by closure of the starting switch, operative to open the relay when the engine starts and a coil connected to the starting circuit and energized by the motor generator for holding the relay open while the engine drives the generator.

4. A single unit starting and generating system as set forth in claim 3 including, further, means for delaying effective re-closure of the relay for a predetermined time after deenergization of the holding coil.

MANUEL I-I. ELKIN. 

